This invention relates to the extrusion and decoration of pastry products.
The application of continuous extrusion to the manufacture of decorated food products, particularly pastry goods, bakery products, articles of confectionery or desserts, for example, ice creams, is known.
The conventional method comprises depositing a continuous strand of pastry material on a moving conveyor belt. The strand may then be manually decorated simply by applying continuous or non-continuous decorative elements. Alternatively, the decoration process may be mechanized, particularly for the application of continuous decorations, by means of extrusion attachments comprising fixed nozzles situated tangentially to the strand and designed, for example, to make a reciprocating movement in a plane parallel to the axis of the strand.
In another known method (U.S. Pat. Nos. 1,714,234 and 4,504,511), a decorated strand of pastry product is formed by means of a nozzle rotating about the axis of flow of the product, of which at least one of the outlet openings is eccentric in relation to the flow axis. The strand in the shape of a spiral or, where appropriate, cable is formed in the empty space at the nozzle exit by virtue of the non-uniform rotation of the eccentric outlet openings. It may be deposited on a moving conveyor belt which does not participate directly in its shaping. The machinery used to carry out this particular method has the advantage that the principal and auxiliary extrusion elements are accommodated in the same extrusion head.
The construction of a rotary extrusion head is relatively complicated. Seals between the moving parts and the fixed parts have to be provided in the nozzle itself together with a mechanism for driving the moving parts. The problem is aggravated where it is desired to obtain decorative strands of complex shape because their shape is imparted solely by the rotation of the nozzle about itself without participation of the surface on which the strands are deposited. Accordingly, a head of the type in question is cumbersome and difficult to clean.